This is an old and very distinct style form the heyday of the Yaogangxian Mine, in the late 1990s through early 2000s, when these sharp and deeply colored purple ice cubes came out. It dates to a time, when relatively few fine specimens came out undamaged and intact. I later obtained it from the Chinese collection of Dr. Steve Smale in Berkeley. Then, I personally carried this gorgeous specimen out of Steve Smale's home after a deal, and down the road to Jack Halpern's where he took it the next day. So it was in not only one, but both of the most prestigious and respected collections of the Bay Area (note that Jack, in a slip of the moment, wrote quartz on the label but it is indeed little blades of white calcite atop and the card matches the piece). It is shockingly sharp and well-defined, and leaps out in a case.